The need for detergent compositions which exhibit not only good cleaning properties, but also good fabric-softening performance, and other fabric care benefits, is well-established in the art.
The efficiency of cellulolytic enzymes, i.e. cellulases, in terms of textile cleaning and harshness-reducing agent for fabrics has been recognized for some time; GB-A-2,075,028, GB-A-2,095,275 and GB-A-2,094,826, disclose detergent compositions with cellulase for improved cleaning performance; GB-A-1,368,599 discloses the use of cellulase for reducing the harshness of cotton-containing fabrics; U.S. Pat. No. 4,435,307 teaches the use of a cellulolytic enzyme derived from Humicola insolens as well as a fraction thereof, designated ACXI, as a harshness-reducing detergent additive.
EP-A-0 269 168 discloses optimized detergent compositions containing cellulase, which are formulated at a mild alkaline pH range and provide combined fabric cleaning, fabric softening, and fabric care performance.
In WO 89109259 have been disclosed cellulase preparations useful for reducing the harshness of cotton-containing fabrics, comprising an endoglucanase component with a high endoase activity and affinity towards cellulose.
The practical exploitation of cellulases has however, been set back by the fact that cellulase preparations such as those disclosed in the above-mentioned prior art documents, are complex mixtures, of which only a certain fraction is effective in the fabric-care context; it was thus difficult to implement cost effective industrial production of cellulase for the detergent industry; and large quantities of such cellulase preparations would need to be applied, in order to obtain the desired effect on fabrics.
Improvements in cellulase production also often have not proven to be sufficiently identifiable in terms of applicability in detergents. Defining a cellulase selection criterium relevant for detergent application of cellulase was made possible by the C14CMC-method disclosed in EP-A-350 098. A minimum of 10% removal of immobilized radioactive labelled carboxymethyl-cellulose has now been found to provide high activity cellulase. A preferred group of cellulase falling under the high activity definition according to the present invention has been disclosed in copending Danish Patent Application No.: 1159/90 filed May 5, 1990. There is amongst others disclosed a cellulase preparation consisting essentially of a homogeneous endoglucanase component which is immunoreactive with a monoclonal antibody raised against a partially purified about 43 kD cellulase derived from Humicola insolens DM1800.
The finding that this particular endoglucanase component of cellulase is advantageous for the treatment of cellulose-containing materials now permits to produce the cellulase cost-effectively, e.g. by employing recombinant DNA techniques, and allows to apply only a small quantity of the cellulase preparation, and obtain the desired effect on fabrics.
EP-A-381 397 discloses the effect of low ionic-strength on enzyme performance, in particular for lipase. However, it has been surprisingly found, that the effect of a compact matrix on the selected enzymes of the present invention is much larger than what could be expected from state of the art cellulases such as disclosed in EP-A-381 397.
In EP-A-177 165 the use of softening clay together with cellulase in detergent compositions has been disclosed. The invention of this disclosure is based on the lack of prior art disclosing the combination of two principal softening or hashness reducing detergent compounds. EP-A-177 165 recognizes that there is no reason to exclude clay or cellulase from detergent compositions comprising the respective other compound. However, EP-A-177 165 does not recognize that for the selected group of highly active cellulase according to the present invention, the combination with clay is advantageous beyond the additive performance which otherwise could be expected of two softening ingredients.
Accordingly, it is an objective of the present invention to provide detergent compositions comprising a high activity cellulase and softening clay, which detergent compositions exhibit an optimum softening performance. An additional objective is to provide such detergent compositions in liquid or granulate form.
It is another objective of the present invention to provide detergent compositions containing high activity cellulase together with softening clay which provide excellent colour rejuvenation and whiteness maintenance for fabrics especially for those which comprise cellulose fibres. An additional objective of the present invention is to provide detergent compositions which further exhibit good stain removal and cleaning performance particularly at temperatures of about 60.degree. C. or below.
It is a further object of the present invention to provide such detergent compositions in a compact form, having a relatively high density and containing a low amount of inorganic filler salt, which exhibit optimum softening performance.
It is yet another objective of the present invention to provide liquid detergent compositions comprising, in addition to the essential compounds of the present invention, an anti-settling agent to provide a storage stable clay suspension matrix. An even further objective of the present invention is to provide detergent compositions, be it liquid or granular comprising in addition to the essential compounds a clay flocculating agent to additionally aid the softening clay deposition on fibres.